1 Radio signals received from the galaxy's centre back up the black hole theory.
2 Within our own galaxy there are probably tens of thousands of planetary systems.
3 Future generations will probably publish guides to the galaxy.
4 At least one supernova occurs per decade in our galaxy.
5 The pressures that would intrude from the galaxy would defeat our purpose.
6 Give me a sky and I'll show you what a galaxy is all about.
7 A string of 13 dwarf galaxies in orbit around the massive galaxy Andromeda are not behaving as they should.
8 To explain this, they hypothesise that galaxies must contain a great deal of missing matter which cannot be detected.